Method and apparatus for the capture of intra-cellular activity

ABSTRACT

An intracellular monitoring device (IMD) that fits completely inside a living cell, and causes no significant impairment, to a cell&#39;s normal biological processes. The IMD monitors a cell for its level of a biological substance (e.g., calcium ion concentration) of interest. If the biological substance reaches or exceeds a threshold, the IMD transmits an electromagnetic signal, received by an antenna outside the cell. Each IMD has its electromagnetic signal encoded with a unique frequency. Detection of the frequency components, in the signals received by an antenna, permits identification of the source IMD&#39;s. A high calcium ion concentration is indicative of a strongly-activated cerebral cortex neuron. Brain tissue is relatively transparent to near infrared, making it a good frequency band, for the electromagnetic signals from neuron-monitoring IMD&#39;s. The near infrared of each IMD can be produced by quantum dots, powered by bioelectric catalysis triggered by high calcium ion concentration.

As provided for under 35 U.S.C. § 120, this patent claims benefit of thefiling date of the following U.S. patent application, hereinincorporated by reference in its entirety: “Method and Apparatus for theCapture of Intra-cellular Activity,” filed 2015 Aug. 24 (y/m/d), havinginventor Bruce T. Hope, Mark A. Wells, and Gregory D. Sutton, andapplication Ser. No. 14/834,334.

As provided for under 35 U.S.C. § 119(e), application Ser. No.14/834,334 claims benefit of the filing date for the following U.S.provisional patent application, herein incorporated by reference in itsentirety:

“Method and Apparatus for the Capture of Intra-cellular Activity,”Application No. 62/041,028, Confirmation No. 1510, and filed 2014 Aug.23 (y/m/d).

FIELD OF THE INVENTION

The present invention relates generally to capturing cellular activity,and, more particularly, to capturing intra-cellular activity with amonitoring device, the monitoring device implanted in each cell to bemonitored.

BACKGROUND OF THE INVENTION

The chemical and electrical processes inside living cells are known tobe extremely complicated, and existing techniques for collection ofinformation on such processes, with sensing apparatus external to thecell, are known to have a variety of significant limitations.

It would therefore be desirable to be able to develop new mechanisms bywhich cellular activity can be monitored.

An example area, where new mechanisms for sensing are particularlydesirable, is the monitoring of neural activity.

Each existing technique, for the capture of neural-activity, fits intoone of the two following categories:

-   -   1. Captures the activity of a large region cortical manner, each        region including at least hundreds of thousands of neurons, but        the activity of individual neurons, within a monitored region,        is unknown. An example technique in this category is functional        magnetic resonance imaging.    -   2. Captures the activity of individual neurons, but only a small        number of adjacent neurons (e.g., on the order of 100) can be        simultaneously monitored. Example techniques in this category        include electrode arrays and calcium imaging.

It would therefore be desirable to have neuronal-activity monitoringsystems that capture both the activity of a large area of neurons and,within that area, activity on an individual-neuron level.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, that are incorporated in and constitute apart of this specification, illustrate several embodiments of theinvention and, together with the description, serve to explain theprinciples of the invention:

FIG. 1A presents an idealized and simplified pyramidal neuron, as can befound in a mammalian cerebral cortex.

FIG. 1B shows the neuron from FIG. 1A providing an output to each of twoneighboring pyramidal neurons.

FIG. 1C shows the same neuron of FIG. 1A, except it includes anintracellular monitoring device.

FIG. 2A presents an example volume of cortical tissue, from a simplifiedand idealized region of the cerebral cortex of a laboratory rat.

FIG. 2B presents same volume of cortical tissue as FIG. 2A, except shownfrom a top view.

FIG. 3A depicts the same cortical volume depicted in FIG. 2A, except anexample antenna 310 is inserted into the cortical tissue.

FIG. 3B presents same volume of cortical tissue as FIG. 3A, except shownfrom a top view.

FIG. 3C is the same as FIG. 3A, except it focuses on two neurons,numbered 300 and 301, within cubic region 312.

FIG. 3D relates neurons 300 and 301, of FIG. 3C, to, respectively, theconnectivity between neurons 100 and 101, as discussed earlier withrespect to FIG. 1B.

FIG. 4A depicts a section of cortical tissue identical to that of FIG.3A, except that, rather than an antenna structure 310, an injectionneedle 410 is shown as having been inserted.

FIG. 4B is similar to FIG. 4A, except it shows a syringe structure, aswell as additional types of tissue, for purposes of providing furthercontext to the injection process.

FIG. 4C is similar to FIG. 3A, but shows how antenna 310 can be securedin-place, with respect to skull surface 432.

FIG. 4D depicts views of the top of antenna 310, labeling its six sidesand illustrating the exiting optical fibers.

FIG. 4E shows each EM collection point being implemented with anano-collimating lens, and each such lens being coupled to an opticalfiber.

FIG. 5A presents two perspective views, 500 and 501, of a same exampleIMD design.

FIG. 5B shows the same two views as are depicted in FIG. 5A, exceptdimensions and regions are labeled.

FIG. 5C depicts NIR as it would radiate, in the X-Y plane, for the IMDdesign of FIGS. 5A-B.

FIG. 6 shows a highly magnified view of region 530, as indicated in FIG.5B, and labels the thicknesses.

FIG. 7A is a highly magnified view of region 531, as indicated in FIG.5B, that shows individual catalyst and linker molecules.

FIG. 7B shows the same highly magnified view of region 531 as is shownin FIG. 7A, but at an earlier point in the manufacturing process, whenonly be linker molecules are attached.

FIG. 8A is a highly magnified view of region 532, as indicated in FIG.5B, that shows individual catalyst and linker molecules.

FIG. 8B shows the same highly magnified view of region 532 as is shownin FIG. 8A, but at an earlier point in the manufacturing process, whenonly be linker molecules are attached.

FIG. 9 depicts an example peptide-coating technique, for the IMDstructure discussed above with respect to FIG. 5A.

FIG. 10 depicts an example signal processing, in the optical andelectrical domains, for each nano-collimating lens of antenna 310.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Reference will now be made in detail to various embodiments of theinvention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same or like parts.

Please refer to Section 10 (“Glossary of Selected Terms”) for thedefinition of selected terms used below.

TABLE OF CONTENTS TO DETAILED DESCRIPTION

1 Overview

2 Pyramidal Neurons

3 IMD Overview

4 Cerebral Cortex Layers

5 Antenna Structure

6 Injection Process

7 EM Collection

8 IMD, Example Construction

-   -   8.1 Overview    -   8.2 Quantum Dot LED    -   8.3 Substrate and Metal Layers    -   8.4 Bioelectrocatalysis        -   8.4.1 Overview        -   8.4.2 Molecular Level    -   8.5 Endocytosis    -   8.6 Inert Coating        9 Computing Equipment        10 Glossary of Selected Terms

1 Overview

Recent research indicates that, within at least higher-order organisms(e.g., the scientific class Mammalia, more commonly known as mammals),it would be desirable to be able to accomplish the following:

-   -   Across a volume of cortical-matter large enough to include, at        least, thousands of active neurons, an ability to individually        monitor the activity of a large number of those neurons (e.g.,        at least hundreds of neurons).

We shall refer to this kind of monitoring capability as “Large ScaleFine Grained” neural monitoring (also referred to herein as “LSFGmonitoring”). LSFG monitoring has many important areas of application,including the following two: development of brain-machine interfaces,and cognitive neuroscience research. Regarding the latter, there is anarea of research based on the organizing principal of “neuronalensembles” (also referred to herein as “neuronal ensemble research”). Anoverview of neuronal ensemble research can be found in the followingpublication, herein incorporated by reference in its entirety:

-   -   “New technologies for examining the role of neuronal ensembles        in drug addiction and fear,” by Cruz et al., in Nature Reviews        Neuroscience, Volume 14, November 2013, 12 pages (“the Cruz et        al. paper”).

Neuronal ensemble research has been useful, for example, in betterunderstanding higher-level cognitive activities, such as a mammal'sability to distinguish the “place” where it is currently located,compared to places (or living environments) where the animal has beenpreviously. An example of this kind of learning, covered in the Cruz etal. paper, is the ability to train a laboratory rat to recognize whereit is placed. The rat learns that when it is in a first cage, with afirst set of environmental queues, it is able to obtain a food or drugreward upon pressing a lever. The rat is also taught that when it hasbeen placed in a second cage, with a second and different set ofenvironmental queues, pressing a similar lever will produce no reward. Astudy discussed in the Cruz et al. paper proved that the cognitiveprocesses of the rat, that enable it to remember one environment asdifferent from another, involve neural ensembles.

A neuronal ensemble can be defined as follows:

-   -   Within a cortical-area comprising at least thousands of neurons,        an ensemble is said to occur when, and only when, a small        percentage of those neurons is strongly activated.    -   A small percentage is a percentage within the range of        approximately 1 to approximately 5%.    -   As an approximate, and representative, value, a neuron is        strongly activated when it consistently produces (e.g., over a        period of approximately one second or more) pulses at a rate of        about 10 Hz. An approximate and representative duty cycle, when        generating 10 Hz, is as follows: for each cycle, approximately        10% of the time (e.g., 10 ms) is consumed producing the pulse        (also called the “action potential”) and 90% of the time (e.g.,        90 ms) is consumed by the neuron's polarization being decreased,        as the neuron prepares to produce a next strong-activation        pulse.

The Cruz et al. paper showed that a rat's memory of being in the firstcage is embodied in a first ensemble, and its memory of being in thesecond cage is embodied in a second ensemble. The study showed that thetwo ensembles are different from each other.

The present invention is based upon a realization that microelectronicshas advanced to a point where it is now possible to implant a monitoringdevice, referred to herein as an “Intracellular Monitoring Device” (orIMD), entirely within a living cell. This monitoring device can be madesmall enough such that it causes, at most, insignificant impairment tothe normal biological processes of the cell in which it is implanted.Thus, while a cell is undergoing its normal biological processes, an IMDcan sense one or more conditions in the cell, and wirelessly transmitthe collected information to one or more receivers placed externally tothe cell.

The IMD can be implanted within a single cell organism, or, for any typeof multi-cellular organism, within the cells of any of its tissue types.

For Mammalia, cells typically range in diameter from about 10-50 μm. Arectangular, box-shaped, IMD, with no edge having a dimension greaterthan 1.0 μm, can be expected to be implantable within any mammalian cellwithin the typical size range.

The example cell type focused-upon herein is the neuron and, moreparticularly, the pyramidal neurons of the mammalian cerebral cortex.Such cells typically have a cell body (or soma) with a diameter rangingfrom 10-20 μm. An example animal addressed herein is the laboratory ratwhere, as a simplified approximation, the cell body of its pyramidalneurons are assumed to have a diameter of 17 μm.

2 Pyramidal Neurons

This section presents a basic overview, of an idealized and simplifiedpyramidal neuron, as can be found in a mammalian cerebral cortex(depicted in FIG. 1A). This overview, and the next section's overview ofcortex layers, are presented for purposes of assuring appropriatecontext, for application of the present invention. There is a vastscientific literature on the structure of neurons and the cerebralcortex, and such literature can be consulted, as necessary, for aparticular application of the invention. Similarly, the presentinvention can be applied to the monitoring of intracellular activity inother types of cells, by consulting the appropriate scientific and/ormedical literature.

While there are many other types of cells within a mammalian brain, thefocus of the present example is on the pyramidal neurons, as these arethe focus of neuronal ensemble research, as discussed above.

The main cell body of a neuron (e.g., neuron 100 of FIG. 1A) is calledthe soma (such as soma 110 of FIG. 1A). As can be seen in the figure,example soma 110 is approximated as a sphere, with its diameter labeled121. Diameter 121 is shown as being 17 μm, used herein as an average,representative value, for the laboratory rat. While an actual soma wouldcontain many other organelles, for purposes of simplicity of exposition,only the nucleus (nucleus 113) is shown for soma 110.

As is well understood in the scientific literature, a neuron receivesinput signals through its dendrites and sends out output signals throughits axons. A synapse is a region where the axon of one neuron sends asignal to the dendrite of another neuron.

A pyramidal neuron is characterized by having two main types ofdendrites:

-   -   Basal dendrites (such as basal dendrite 112), that, in general,        extend laterally from the soma. Taken together, the lateral        directions of the basal dendrites can be summarized as defining        a kind of plane, relative to a neuron's soma.    -   An apical dendrite (such as apical dendrite 111), that extends        in a direction that is, in general, perpendicular to the plane        defined by the basal dendrites. An apical dendrite is often        quite long, and typically crosses through other “layers” of        neurons (the six main layers, of cerebral cortex pyramidal        neurons, are presented below).

Each basal dendrite can have one or more branches, such as dendriticbranch 118 of FIG. 1A. The apical dendrite also has, in general, one ormore dendritic branches.

When a neuron “decides” (as a result of receiving sufficient inputs atits dendrites) to output a signal, the signal begins at the neuron'shillock (such as hillock 115). The signal travels away from the neuron'ssoma via its axon, and axon branches (an axon branch is referred to as a“collateral,” such as collaterals 116 and 117 of FIG. 1A). The traversalof a signal, along a neuron's axon, is referred to as an “actionpotential.” An action potential “moves” as a result of a kind of rollingwave of depolarization, followed by re-polarization, in anelectrochemical process.

FIG. 1B shows another copy of neuron 100 (from FIG. 1A), but now neuron100 is shown as providing an output to two neighboring pyramidalneurons: neuron 102 and neuron 101. A connection, from an output ofneuron 100 to an input of neuron 102, is indicated as a synapse 130 inFIG. 1B. Similarly, a connection, from an output of neuron 100 to aninput of neuron 101, is indicated as a synapse 131 in FIG. 1B. The sideof synapse 130 formed by neuron 100 is indicated in FIG. 1A as axonterminal 122. Similarly, the side of synapse 131 formed by neuron 100 isindicated in FIG. 1A as axon terminal 123. Each of neurons 102 and 101forms its side of, respectively, synapse 130 and 131, from the dendriticspine that is, respectively, closest to axon terminal 122 or 123. Ingeneral, a dendritic spine is a spike-shaped structure that is, relativeto the length of the dendrite to which it is attached, quite small. Anexample dendritic spine 120, for neuron 100, is indicated in FIG. 1A.

As is well known, the axon terminal side of a synapse emits molecules ofa chemical called a neurotransmitter. The neurotransmitter molecules arereceived by the dendritic spine, on the receiving side of a synapse.

3 IMD Overview

FIG. 1C depicts another copy of neuron 100 (already discussed above withrespect to FIGS. 1A and 1B), but in FIG. 1C neuron 100 is shown ascontaining an Intracellular Monitoring Device (or “IMD”), labeled 140.

An IMD, as described herein, includes at least the followingcharacteristics:

-   -   1. The IMD is small enough such that it can fit entirely inside        a living cell, while causing, at most, insignificant impairment        to the cell's normal biological processes. To accomplish this,        the longest dimension of an IMD is typically limited to being no        more than approximately 1 μm. FIG. 1C is intended to show        relative scale, between IMD 140 and soma 110, where IMD 140 is a        1 μm square (and, as stated above, soma 110 has a 17 μm        diameter).    -   2. The IMD collects data, regarding at least one biological        process of the cell in which it is contained (hence, it is an        intracellular monitoring device).    -   3. The IMD transmits an electromagnetic (or EM) signal, that is        both indicative of the particular IMD from which it originates,        and that also communicates information, regarding the at least        one biological process it has been monitoring.

When used as part of a system for intracellular monitoring, an antennais placed sufficiently close to the IMD, such that the IMD's EM signalcan be received, and then analyzed for its informational content.

For an IMD to be “entirely inside a living cell” means that the IMD iscompletely within the cell membrane (also called a plasma membrane orcytoplasmic membrane) of the cell it is to monitor. Being completelyinside a cell is compatible with an IMD being in contact with the cellmembrane, just so long as this contact is with the interior wall of thecell membrane.

Further aspects, of IMD design, can include the following:

-   -   Selection of its EM spectrum for transmission:        -   Depending upon the type of living tissue, whose cells are to            be monitored, a suitable “wavelength window” can be            determined. This is a range of spectrum for which the            relevant tissue presents minimal attenuation, or, at least,            an acceptable level of attenuation.        -   With regard to cortical brain tissue, measurements have            shown that it is most transparent to that portion of the EM            spectrum called “Near-Infrared” (or NIR). For this reason,            when applied to the monitoring of cortical neurons, a            preferred embodiment of IMD uses NIR to transmit its            information. More specifically, NIR that is approximately            within the following range of wavelengths is preferred: 700            nm-1100 nm. To show how important the correct choice of            spectrum can be, the below table summarizes the difference            in attenuation, between use of the visible light or NIR:

Tissue traversed Attenuation of Visible Attenuation of NIR 1 mm 64%-99%14% 1 cm 99.9996% 64%As can be seen, even after passing through 1 cm of cortical tissue, NIRis attenuated by only 64%. In comparison, over the same distance, thevisible spectrum is attenuated 99.9996%.

-   -   Selection of a device for generating the IMD's EM transmission,        and a technique by which the particular IMD, that is the source        of a particular EM transmission, can be identified:        -   With regard to the production of NIR radiation, quantum dots            are a suitable technology.        -   Because a quantum dot can be precisely tuned, regarding the            frequency of NIR it emits, it is also a good technology for            encoding, in the EM transmission, the identity of the            particular IMD that is the transmission's source. For            example, all the quantum dots for each IMD can be tuned to a            specific and unique frequency—it is only necessary that all            the quantum dots of an IMD have the same diameter. In this            way, 100's of different QD-LED's can be produced, each with            its own unique and precisely-tuned frequency.        -   NIR Light-Emitting Diodes (LED's) can be used as the EM            source for an IMD. However, NIR LED's are, in general,            available in a smaller variety of different frequencies            and/or more difficult to precisely tune to a particular            frequency. This makes it difficult to separately monitor            100's of IMD's by simply assigning each its own frequency            within the NIR band (see Section 7 “EM Collection”).    -   Selection of the biological processes to be monitored, and the        techniques for capturing the information:        -   With regard to cortical brain tissue, and, more            particularly, the detection of ensembles, it has been            determined that a high concentration of calcium ions, in a            neuron's soma, is a reliable indicator of whether that            neuron is strongly activated. This means that a neuron,            during the period of time when it is strongly activated and            is actually producing a pulse, its calcium level is high.            During its period of decreasing polarization, when the            strongly-activated neuron is preparing for production of a            next pulse, its calcium ion concentration initially starts            out low. At, or shortly before, the point in time when            depolarization is sufficient to cause the neuron to “fire”            (i.e., produce an action potential), the calcium ion            concentration reaches its approximately maximal levels        -   An example technique, for causing an IMD to detect the high            calcium levels associated with strong activation, is called            bioelectrocatalysis. More specifically, an IMD can be            equipped with an enzyme. The enzyme enables production of an            electric current only when a threshold calcium level,            corresponding to strong activation of a neuron, is reached.            Utilization of this calcium-dependent electric current, to            trigger a coded NIR transmission by an IMD, can be            accomplished with any suitable technique. An example            technique, covered in more detail in a following section, is            to use this calcium-dependent electric current as part of            the main power supply of an IMD. Thus, when the            calcium-dependent electric current is being produced for an            IMD, that IMD is “powered-up.” An IMD can be designed so            that, as long as it has power, it continuously transmits a            particular frequency of NIR radiation.    -   Providing power for the IMD. As discussed above, this can be        provided by bioelectrocatalysis, with the beginning of the        bioelectrocatalysis also being a signal, indicating that the        monitored biological process has reached a threshold of        interest. Alternatively, or in addition, an IMD can be powered        by EM radiation it is designed to receive. For example, the IMD        can contain a dipole antenna, for receipt of such broadcast        power.

4 Cerebral Cortex Layers

As discussed above, for purposes of neuronal ensemble research, it wouldbe extremely useful to have the ability to accomplish LSFG monitoring ofcortical tissue. FIG. 2A presents an example appropriate volume ofcortical tissue, from a simplified and idealized region of the cerebralcortex of a laboratory rat. FIG. 2A depicts a cylindrical volume, with adepth 202 and a radius 201. Depth 202 is the full depth of the cerebralcortex. Depth 202 is 1.4 mm, used as an average, representative value,for the laboratory rat. Radius 201 is chosen to be 1.0 mm. (In FIG. 2A,radius 201 is represented by a 10 cm distance, and thus the figurerepresents an approximately 100× magnification, of the actual corticaldistances.) The cylindrical volume is contained within upper circle 220and lower circle 226, where 220 represents the cortical surface (e.g.,the layer of cortex closest to the skull).

It is standard nomenclature to divide the cerebral cortex, along itsdepth dimension, into six different layers of pyramidal neurons,numbered I to VI (see left side of FIG. 2A, for this numbering oflayers). The six layers are divided from one another, in the figure, bycircles 221-225 (the circles representing a simplification andidealization, for purposes of exposition, of the clarity of divisionbetween layers). The correspondence, between a neural layer and a pairof labeled circles, is as follows:

-   -   Layer I: between 220, and 221.    -   Layer II: between 221, and 222.    -   Layer III: between 222, and 223.    -   Layer IV: between 223, and 224.    -   Layer V: between 224, and 225.    -   Layer VI: between 225, and 226.

Per the following estimations, it will be shown that just the smallcylindrical region of FIG. 2A (diameter 2.0 mm, depth 1.4 mm) containsapproximately 3.0×10⁵ neurons.

First, along the X-Y plane (as indicated by set of axes 200), pyramidalneurons are generally packed quite tightly together. Thus, along aradius of 1.0 mm, one can expect approximately 50 neuron somas. Tosuggest this density of packing, a line of approximately 50 somas isshown, in FIG. 2A, just below radius 201.

Along depth 202 (the Z axis, as indicated by axes 200), are shown 37neurons (where 37 is used as an average, representative, value). Tosuggest the way in which the density of these 37 neurons can be expectedto vary, across the layers, the left side of FIG. 2A shows a column of37 neuronal somas. As can be seen, all 37 somas are shown as being inlayers II to V. This is because layers I and VI are used almost entirelyto provide space for inter-neuron “wiring.” Among layers II to V, layerIII is indicated as having 7 neurons along its depth (as an average,representative, value), while each of layers II, IV, and V, is indicatedas having 10 neuron somas. This difference is due to the fact that,generally, layer III has fewer neurons, than are present in layers II,IV, and V.

Given the densities presented in the prior two paragraphs, the totalnumber of neurons, in the cylindrical area of FIG. 2A, can be estimated.First, the number of neurons for each circular area, where that circulararea has only one neuron along its depth, can be found by application ofthe formula: Area=πr². Using 50 as the value for r, we find that thereare approximately 8000 neurons, in each circular “slice” of thecylinder. A top view of an example circular slice of cortex, along theX-Y plane, is shown in FIG. 2B. This figure depicts approximately 8000somas, within a circle drawn at scale of approximately 100×. Second, thetotal number of neurons, expected to be found in the cylindrical area,is then found by simply multiplying the value for a circle (8000) by thetotal number of such circles expected, along depth dimension 202(corresponding to the Z axis):(8×10³)×(37×10⁰)=296×10³ (i.e., about 300K neurons)

Although FIG. 2A is drawn as mostly empty space, the actual corticalvolume it represents is packed, quite densely, with neuron somas. Toassist the viewer with imagining this density, a cubic area 212 isshown. Cubic area 212 is drawn as having approximately 5 somas, alongall three dimensions, with each dimension of the cube being,approximately, 100 μm. To more clearly represent its shape, cubic area212 is shown as corresponding to a cube outline 213.

5 Antenna Structure

Any suitable antenna structure can be used, depending upon such factorsas:

-   -   The portion of EM spectrum utilized by the IMD.    -   The type of tissue to be monitored.    -   The environmental situation, in which the complete monitoring        system is operating.

FIG. 3A depicts the same cortical volume depicted in FIG. 2A, except anexample antenna 310 is inserted into the cortical tissue. Antenna 310 isdesigned under the assumption that the IMD's, whose signals the antennais designed to receive, are transmitting in the NIR part of thespectrum. The antenna is shown as a hexagonal structure, with a diameterof about 200 μm. For each of the six sides, there are shown four pointsfor collection of EM radiation: one collection point for each of layersII to V. A close-up depiction of the top of antenna 310 is shown in FIG.4D. Proceeding in a clockwise fashion, from the side farthest from theviewer of FIG. 3A, these sides are numbered: 450-455. For FIG. 3A, onlythree sides, of hexagonal antenna 310, are visible (corresponding tosides 452-454). Among the three visible sides, the middle side (453) hasits EM collection points labeled: 320-323. While antenna 310 is shown ashaving six sides, any number of sides, suitable for the particularapplication, can be used. Furthermore, while only four collection pointsper side are shown, any number of EM collection points, suitable for theparticular application, can be used.

FIG. 3B depicts the same top view of the cortical volume, as is shown inFIG. 2B, except that antenna 310 is shown as having been inserted. FIG.3B also indicates that, per volume calculations, a 200 μm diameterantenna displaces about 1%, of the cortical neurons in that volume (80neurons of 8000, for each of the approximately 37 neuronal layers, alongdepth 202). In general, this level of displacement can be expected tocause, at most, insignificant impairment to the normal functioning ofthe cortical matter into which it is inserted.

To (once again) suggest the density of neurons, across the corticalvolume, cubic regions 312 and 313 are shown in FIG. 3A. These regionscorrespond to, respectively, 212 and 213 of FIG. 2A.

To provide some suggestion of inter-neuron connectivity, FIG. 3C focuseson two neurons, numbered 300 and 301, within cubic region 312. In FIG.3D, each of neurons 300 and 301 is related to, respectively, theconnectivity between neurons 100 and 101, as discussed earlier withrespect to FIG. 1B. Thus, an axon collateral of neuron 100 is shown asconnecting, laterally and within Layer II, to a dendritic branch ofneuron 101. The apical dendrites, of both neuron 100 and neuron 101, areshown as extending upwards, into Layer I, before branching laterally tomake connections with other neurons. Also, the main axon of neuron 100is shown extending lower, down into Layer III. Of course, these fewconnections, provide only the most minimal hint, of the incrediblerichness of interconnectivity characteristic of mammalian corticalmatter.

6 Injection Process

With regard to cortical tissue, IMD's can be applied to neurons throughan injection process. FIG. 4A depicts a section of cortical tissueidentical to that of FIG. 3A, except that, rather than an antennastructure 310, an injection needle 410 is shown as having been inserted.Compared to antenna 310, injection needle 410 is shown as being insertedonly approximately halfway, into the depth of the cortical tissue (forthe example cortical depth of 1.4 mm, injection depth 411 is shown asbeing approximately 0.7 mm). Injection needle 410 can be, for example, a33 gauge blunt-ended needle (which has an outer diameter ofapproximately 200 μm).

FIG. 4B shows injection needle 410 coupled to a suitable syringestructure 412 that is supplied with any suitable injection fluid. Forexample, a phosphate buffered saline (PBS) solution can be used as theinjection fluid. In this PBS solution can be suspended the IMD's.

Compared to FIG. 4A, FIG. 4B also shows additional types of tissue, forpurposes of providing further context to the injection process. Inparticular, FIG. 4B shows additional tissue for a mammalian organism(e.g., a laboratory rat) into which the IMD's are to be introduced:

-   -   A layer 432 of skull is indicated, through which a burr hole is        shown as having been already drilled.    -   Also indicated in FIG. 4B is dura mater layer 431, and cortical        surface 430.

For both FIGS. 4A and 4B, an injection process is depicted that is justin its beginning stages. While at least hundreds of IMD's would besuspended in the PBS solution, as part of a typical injection process,for simplicity of exposition, FIG. 4B depicts only 7 IMD's, numbered420-426. IMD's 424-426 are shown as still being in syringe section 412,while IMD's 421-423 are inside injection needle 410. Only IMD 420 isshown as having exited injection needle 410, along a trajectory labeled412 (see FIG. 4A). Also, in FIG. 4A, IMD 420 is also shown as being inproximity to neurons located at cubic region 413. Actual entry of anIMD, into the soma of a neuron, is addressed in a following section thatcovers the inducement of endocytosis.

A sufficient concentration of IMD's can be suspended, such that only asmall amount of the PBS solution (e.g., 0.5 microliters) need beinjected at each cortical area where IMD's are to be introduced.Further, it is generally advantageous to apply the injection fluidslowly, at each injection site (e.g., over a two minute period).Concentration of IMD's, to a volume of injection fluid suitable to theparticular application, can be achieved, for example, by use of acentrifuge.

Because of their small size, the IMD's can be expected to distributethemselves throughout the tissue area that is in proximity to eachinjection site, in a manner similar to that achieved when particularmolecular compounds are injected into various kinds of tissue. The fluiddynamics, of the PBS solution as it comes into contact with the corticaltissue, can be expected to exhibit various flow patterns, which aid inan even distribution, among the cells of the cortical tissue to bestudied. Further, the IMD's themselves are sufficiently small, such thatthey can be expected to undergo secondary effects, such as Brownianmotion, that also encourage a more uniform distribution, of IMD's withinthe cortical cells.

Once injection of the IMD's has been accomplished, injection needle 410can be removed, and, as is shown in FIG. 4C, replaced with an antenna310. The drawing of FIG. 4C is the same as FIG. 3A, except the broadercontext, of mammalian bodily tissue, is shown. As can be seen, antenna310 can be secured in-place, with respect to skull surface 432, by theapplication of dental cement 440.

7 EM Collection

Once IMD's have been placed inside the cells to be monitored, and anantenna is in-place with respect to the tissue to be monitored, theantenna can be used to collect EM transmissions from the IMD's.

As discussed previously, the particular example structure, of antenna310, has four EM collection points per side. Further, antenna 310 has ahexagonal structure, meaning there are a total of 24 EM collectionpoints. With respect to IMD's transmitting in the NIR part of thespectrum, each collection point can be implemented with a collimatinglens, referred to herein as a nano-collimating lens (or NCL). Each NCLcan be coupled to an optical fiber, such that the NIR signals receivedcan be transported to appropriate receiving equipment.

An example of this approach is shown in FIG. 4E, where EM collectionpoints 320-323 are shown as each being implemented with an NCL and eachof the NCL's is coupled to, respectively, one of optical fibers4530-4533. FIG. 4D shows that, following this approach, 24 opticalfibers emerge from top-surface 441 of antenna 310. Four optical fibersare shown emerging from each of the six sides of antenna 310, the sidesnumbered (clockwise) 450-455. For an antenna 310 with a diameter of 200μm, it can be seen that each side of the antenna is 100 μm wide, meaningthat each NCL needs to have a diameter less than 100 μm.

The 24 optical fibers, coupling antenna 310 to the receiving equipment,can be of a length suitable for the particular experimental situation.For example, if the optical fibers couple a laboratory rat to thereceiving equipment, and the ensembles of rat cognition are to bestudied (e.g., see above discussion of the Cruz et al. paper), it isnecessary the optical fibers are of sufficient length, such that the ratcan have sufficient mobility, when interacting with an environment inwhich it is placed. Optical fibers, without any further structuralsupport, are fragile. Any suitable cabling technique can be used, towrap the 24 fibers in a suitably strong protective covering.

FIG. 10 depicts an example coupling, between a single NCL and itsreceiving equipment. In FIG. 10 , antenna 310 is represented by dottedoutline 1000. Within this outline, only a single NCL 1001 is shown(although a total of 24 NCL's would be needed). The NIR collected by1001 is directed along an optical fiber 1002. Fiber 1002 is sized to beof sufficient length, such that it provides suitable mobility for a testanimal (the variable length of 1002 represented by break 1003).

The “NCL Receiving Equipment,” as that term is used herein, consists ofall the equipment in FIG. 10 that is coupled to the output of fiber1002. The NCL Receiving Equipment begins with optical amplifier 1010,which is driven directly by the output of fiber 1002. Optical amplifier1010 then drives, directly or indirectly, all the other NCL ReceivingEquipment for NCL 1001. Optical amplifier 1010 is the first component ofthe NCL Receiving Equipment because the NIR signal, expected to beprovided at the output of fiber 1002, is otherwise too attenuated forfrequency analysis. Any suitable optical amplification technology can beused, so long as it includes at least the following characteristics:

-   -   only increases the amplitude, of the NIR collected by its NCL;    -   does not remove or add any frequency components; and    -   relative amplitudes, between frequency components, is unchanged.

Only a single copy of the NCL Receiving Equipment of FIG. 10 is shown,since it is only necessary to provide a copy, of the same apparatus, foreach of the 23 other NCL's.

The output of optical amplifier 1010 is subjected to, in the opticaldomain, a frequency analysis. As was discussed above, a technique foridentifying the IMD, that is the source of a particular signal, is toassign each IMD a unique frequency, where all such frequencies chosenare within the NIR band of EM radiation. Thus, a task of the NCLReceiving Equipment can be to determine which frequencies, of thefrequencies assigned to IMD's, are present in the collected signal. Thistask can be accomplished by equipping the NCL Receiving Equipment witheither a set of optical notch filters (one for each of the possible IMDfrequencies), or by using an optical spectrum analyzer, such as aspectrum analyzer based upon a diffraction grating. FIG. 10 presents theapproach of using a set of optical notch filters.

Specifically, FIG. 10 presents the use of Fiber-Bragg Gratings (FBG's),where each FBG is tuned to a wavelength to be detected. While only threeFBG's are explicitly shown in the FIG. 10 (numbered 1021, 1023, and1025), FIG. 10 makes it clear that, in general, the apparatus cancontain “n” FBG's:

-   -   FBG 1021 is tuned for a wavelength λ1;    -   FBG 1023 is tuned for a wavelength λ2; and    -   FBG 1025 is tuned for a wavelength λn.

Based on the NCL Receiving Equipment architecture of FIG. 10 , “n” isexpected to be in the following range:(approximately 100)≤n≤(approximately 1000)

Using the approach of assigning a unique frequency to each IMD, thismeans injecting 100 to 1000 IMD's within each separately-monitoredregion of cortical tissue.

An FBG works as a kind of specialized optical fiber. Light input to it,which is not of the frequency for which it is tuned, simply passesstraight through. However, if the input light has a component that is atthe FBG's frequency, that component is reflected backwards, towards theinput to the FBG. This filtering property, of an FBG, can be utilized bycombining the FBG with another kind of optical device, called an“optical circulator.” For the NCL Receiving Equipment of FIG. 10 , forexample, optical circulator 1020 is the only component directlyconnected to the output of optical amplifier 1010.

Before describing how an optical circulator can be used with an FBG, itis useful to describe how it operates on its own. As shown in FIG. 10 ,each optical circulator has three connection points or ports: aleft-side port, a right-side port, and a bottom port. All light enteringthe left-side port simply passes straight through, and exits at theright side port of the optical circulator. Any light entering theright-side port, however, does not pass straight through, and does notexit at the optical circulator's left side port. Rather, such light isdirect downwards, and exits from the bottom port of the opticalcirculator.

The combination of optical circulator 1020 and FBG 1021 works asfollows. First, all light entering the left port of optical circulator1020 simply passes through, and exits the right port. The light exitingthe right port then enters FBG 1021. If the light entering FBG 1021contains no λ1 component, all the light simply passes straight through,and enters the next stage of filtering (comprised of optical circulator1022 and FBG 1023).

To the extent the light entering FBG 1021 contains a λ1 component, thepath of this component is as follows. It is reflected backwards, andinto the right port of optical circulator 1020. The λ1 NIR then exitsthe bottom port of optical circulator 1020. This emerging NIR of λ1 isdetected by a photodetector 1030. Photodetector 1030 is shown as aphotodiode, but any suitable photodetecting technology can be used. Forexample, CCD-based photodetectors are suitable. The current produced byphotodetector 1030 is then amplified, so that it can be sampled, withthe samples digitized by an Analog-to-Digital Converter (or ADC) 1032.The output of photodetector 1030 is shown as being amplified by adifferential amplifier 1031, but any suitable amplifier can be used. Ascan be seen, the lower port of optical circulator 1020 is separated fromphotodetector 1030 by a dashed line 1004. Dashed line 1004 is meant toclarify the transition, within the NCL Receiving Equipment, from theoptical domain of signal processing to the electrical domain.

The net effect, of optical circulator 1020 and FBG 1021, is that theyact as an optical notch filter, directing any λ1 component though thecirculator's bottom port, and directing any non-λ1 NIR to the nextoptical notch filter.

In the case of FIG. 10 , the next optical notch filter is formed fromoptical circulator 1022 and FBG 1023. This second notch filter works thesame as the first, except it filters for a λ2, rather than λ1. Just aswith the λ1 filter, any λ2 component, to the light that enters the leftport of optical circulator 1022, is reflected backwards, by FBG 1023,and into the right port of optical circulator 1022. This λ2 NIR exitsthe bottom port, where it can then be detected by photodetector 1040.The transition from optical to electrical domain is once againemphasized by dashed line 1004, which is in-between optical circulator1022 and photodetector 1040. The photodetector's output is once againamplified (this time by 1041), sampled, and digitized (this time by ADC1042).

As discussed above, this type of linear chaining, of optical notchfilters, can be extended to the point where it includes filters forhundreds of specific wavelengths. To achieve filter chains of 100, ormore, filters in length, there is a periodic need for additional opticalamplifiers, such that the passed-through NIR can be boosted back to asufficient amplitude for further frequency analysis. The periodicinclusion of one or more additional optical amplifiers is represented,in FIG. 10 , by optical amplifier 1011. It is necessary that eachadditional optical amplifier share the same three characteristics,listed above, for optical amplifier 1010.

The outputs of all the various filter stages, for the NCL ReceivingEquipment of FIG. 10 , are shown feeding into a common Digital SignalProcessing (DSP) block 1060. DSP 1060 can be used to identify all thepulses received, by NCL 1001, that correspond to a strongly activatedneuron. For all “n” wavelengths monitored by the NCL ReceivingEquipment, DSP 1060 can output a data stream representing the pulsesdetected. The ADC's, whose outputs feed into DSP 1060, need to sample ata sufficiently high rate, such that the strong-activation neural pulsescan be detected. As discussed above, a typical pulse width is 10 ms.However, to provide support for a broader range of neural pulses, theADC's can be designed, for example, for neural pulse widths as small as1 ms. To satisfy the minimum Nyquist sampling rate, this corresponds toeach ADC sampling at 2 kHz. To provide extra resolution, beyond thisminimum, each ADC can sample at, for example, 10 kHz.

In order to be able to compare the amplitudes of pulses detected at eachparticular A, across the outputs of all 24 DSP blocks (because there isone DSP block for each copy of NCL Receiving Equipment), it can beuseful to match characteristics, across all 24 optical amplifiersoccupying a same location in the chain of notch filters. The outputs ofthe 24 DSP blocks can then be combined, using any suitablepulse-matching techniques, to produce a single reconstructed stream ofstrong-activation neural pulses. For example, the following types ofpulse-matching techniques can be used:

-   -   Detecting an IMD pulse from multiple NCL's, at the same time,        can increase confidence in a conclusion that a true IMD pulse        had been detected.    -   Among the NCL's that receive a same-frequency IMD pulse at a        same time, the amplitude of the pulse can be set as equal to the        strongest amplitude detected.    -   A structured searched can be performed, of the 24 data streams,        in order to obtain some location information on the source of an        IMD pulse. For example, for a hexagonal antenna, since any three        consecutive sides represent 180°, an IMD pulse can be received        by, at most, three sides. For any one IMD pulse, the sides that        detected it can be found by searching through all six possible        combinations of three consecutive sides. For each of these six        possibilities, the following can be performed:        -   For each pulse detected by one or more NCL's of the middle            side, it can be pattern-matched against the pulses found by            its two adjacent sides.        -   If the middle side detects a pulse with the greatest            amplitude, compared to the greatest amplitude detected for            the same pulse at the other two sides, we can conclude that            the IMD, that generated the pulse received by the middle            side, must be most directionally aligned with that middle            side.        -   On the other hand, if a pulse detected by the middle side            has a greater amplitude at one of the adjacent sides,            analysis of that pulse can be deferred, until that adjacent            side is considered as the central side.

8 IMD, Example Construction

8.1 Overview

An example specific structure for an IMD, along with techniques for itsmanufacture, is covered in this section.

FIG. 5A presents two perspective views, 500 and 501, of a same exampleIMD design. The main body of the IMD is shown, in view 500, as beingconstructed from a substrate 520, that has its major dimensions in theX-Y plane (as indicated by set of axes 503).

On this substrate have been manufactured the following layers, startingfrom the layer that is directly in contact with the substrate andproceeding upwards (these layers have the same dimensions, along the X-Yplane, as 520):

-   -   P-type layer 522;    -   Quantum dot (or QD) layer 523; and    -   N-type layer 521.

In the X-Y plane, example dimensions for layers 520-523 is 1000 nm (or 1μm) per side, forming the shape of a square. This dimensionality can beseen from scale 502 (see bottom of FIG. 5A). Also, FIG. 5B shows thesame two views as are depicted in FIG. 5A: views 500 and 501 of FIG. 5Aare the same as, respectively, views 504 and 505 of FIG. 5B. In view504, the dimensionality of layers 520-523, along the X-Y plane, areindicated as distance 540 (along the X axis) and distance 541 (along theY axis). Further, view 504 highlights a corner of this four-layerstructure, indicated by dashed outline 530. The corner is depicted, inmagnified form, in FIG. 6 .

FIG. 6 shows the thickness (i.e., the distance along the Z dimension),of each of layers 520-522, as, respectively, distances 610-612. Fromscale 502, at the bottom of FIG. 5A, each of layers 520-522 can beestimated as having, respectively, the following approximate thickness:distance 610 is 75 nm, distance 611 is 50 nm, and distance 612 is 50 nm.An example range of thicknesses, for quantum dot (or QD) layer 523, isabout 2 nm to 10 nm. Adding together the thicknesses, of layers 520-523,results is a net thickness (indicated as distance 542 in view 504 ofFIG. 5B) of about 177 nm to 185 nm (depending upon the thickness ofquantum dot layer 523).

8.2 Quantum Dot LED

Layers 521-523 form the core of a Quantum Dot Light-Emitting Device(also called a QD-LED). Quantum dot layer 523 emits light when thevoltage, between P-type layer 522 and N-type layer 521, is at or above athreshold voltage (that we shall refer to as V_(TH)). For the row ofquantum dots, on each of the four 1 μm sides of the IMD, an example pathfor the radiant flux (e.g., NIR) produced, when at least V_(TH) isapplied, is shown in FIG. 5C. FIG. 5C depicts NIR as radiating only inthe X-Y plane, for simplicity of illustration. In general, however, NIRcan be expected to radiate, from each 1 μm side, at angles projectingboth above and below the X-Y plane.

A wide range of QD-LED designs are known, and a suitable QD-LED designcan be chosen, depending upon the particular application. For example,QD-LED design is discussed in the following publications, each of whichis herein incorporated by reference in its entirety:

-   -   “Tuning the performance of hybrid organic/inorganic quantum dot        light-emitting devices,” by Coe-Sullivan et al., in Organic        Electronics, Volume 4, September 2003, pages 123-130 (“the Coe        et al. paper”); and    -   “Contact Printing of Quantum Dot Light-Emitting Devices,” by Kim        et al., in Nano Letters, Volume 8, No. 12, Nov. 2008, pages        4513-4517 (“the Kim et al. paper”).

In such designs, based on the Organic Light-Emitting Diode (OLED), theN-type and P-type layers are often referred to as, respectively, theElectron Transport Layer (ETL) and the Hole Transport Layer (HTL). Asthe name implies, both layers are constructed from organic materials.For example, the Coe et al. paper and the Kim et al. paper describe thefollowing:

-   -   an organic compound known by the acronym “TPD” as an example HTL        material;    -   an organic compound known by the acronym “Alq₃” as an example        ETL material; and    -   CdSe as an example compound for the QD's.

QD's can be formed from a variety of different compounds, besides CdSe.Alternative compounds are discussed in such publications as thefollowing, herein incorporated by reference in its entirety:

-   -   “Size-dependent band gap of colloidal quantum dots,” by        Baskoutas et al., in Journal of Applied Physics, Volume 99,        Issue 1, January 2006, 4 pages (“the Baskoutas et al. paper”).

In addition to CdSe, the Baskoutas et al. paper discusses the following,as materials from which QD's can be formed: CdS, CdTe, PbSe, InP, andInAs. InAs can be a particularly good material from which to make QD's,because it can result in QD-LED's that require a lower threshold voltage(or V_(TH)). For the specific embodiment of the invention discussedherein, where power is provided by a process called bioelectrocatalysis(as described below in Section 8.4), this property can be useful.

The overall principle of operation of a QD-LED, when a sufficientthreshold voltage is applied, is as follows. The applied electric fieldcauses electrons from the ETL (e.g., layer 521) and holes from the HTL(e.g., layer 522) to move toward the QD layer (e.g., layer 523), that isbetween the ETL and HTL layers. The electrons and holes are bothcaptured by the quantum dots, where they recombine, resulting in theemission of photons.

As between HTL and ETL materials, it is generally the case that organicHTL materials transport holes more effectively than ETL materialstransport electrons. If not compensated for, this leads to anundesirable tendency for electrons and holes to combine closer to thesource of the electrons, than to the source of the holes, reducing thenumber of electron-hole recombinations that could otherwise occur in theQD layer. This problem tends to be addressed by adding a hole-blockinglayer, at an appropriate location in-between the ETL and HTL. An examplehole-blocking material, discussed in the Coe et al. paper and the Kim etal. paper, is an organic compound known by the acronym “TAZ.” This typeof hole-blocking layer is not shown in either of FIG. 5A or 5B. Otherpotential refinements for a QD-LED are also not shown in the figures, asthey are not relevant to the present invention, but can be added, asneeded, for particular applications.

8.3 Substrate and Metal Layers

An example semiconductor manufacturing process by which a suitablesubstrate, for the three above-described layers (layers 521-523), can beconstructed, is called Silicon on Sapphire (or “SOS”). The presentinvention utilizes semiconductor fabrication technology in a way that iscounter to one of the industry's major trends: the trend towards largerdie sizes. SOS is a particularly good process for the present inventionbecause of the very small die size (e.g., 1 μm by 1 μm) needed for anIMD. These dimensions are much smaller than what is typically required,from an integrated circuit fabrication process. Prior to the presentinvention, die have almost always had a per-side length in the range of1.0×10⁻³ m to 2.0×10⁻² m. Thus, the IMD die size of 1.0×10⁻⁶ m is atleast three orders of magnitude smaller than the low-end of conventionaldie sizes.

Typically produced by use of a diamond saw, die are cut from a muchlarger wafer (e.g., common semiconductor processes handle wafers with adiameter in the range of about 70 mm to 300 mm). In general, in anon-SOS process, when the wafer is cut to create die that are of a sizerequired by the present invention, the likelihood is much greater forsubstrate cracking. However, SOS is only an example, and any otherfabrication process, so long as it has similar resistance to cracking(and sufficiently small feature sizes), can be used.

The other major industry trend, towards smaller feature sizes, is usefultowards the construction of more sophisticated IMD's, but die sizeitself is limited, due to the size of a biological living cell.

On top of N-layer 521 are shown two additional layers (starting from thelayer that is directly in contact with 521 and proceeding upwards):

-   -   Metal layer 525, shown as being about 25 nm along the Z        dimension.    -   Bioelectrocatalysis layer 524, the thickness of this layer        depending upon the particular enzyme used.

As with layers 520-523, layers 524-525 also have their principaldimensions in the X-Y plane, but, within that plane, layers 524-525occupy less area (e.g., pictured in FIG. 5A as occupying about ¼ to ⅓the area of layers 520-523, and generally centered within that area).

View 501 of FIG. 5A shows the same IMD of view 500, but the IMD has beenrotated. View 501 depicts an axis 510, about which the IMD of view 500has been rotated, in the direction indicated by 511. This rotationpermits the “underside” of the IMD to be seen in view 501. The undersideof the IMD is very similar to its top. Below substrate 520 are shown twoadditional layers (starting from the layer that is directly in contactwith 520 and proceeding downwards):

-   -   Metal layer 526, shown as being about 25 nm along Z dimension.    -   Bioelectrocatalysis layer 527, the thickness of this layer        depending upon the particular enzyme used.

As with layers 524-525, layers 526-527 also have their principaldimensions in the X-Y plane, and, within that plane, occupy less areathan layers 520-523 (e.g., pictured in FIG. 5A as occupying about ¼ to ⅓the area of layers 520-523, and generally centered within that area).However, other than a need to provide sufficient room for inducement ofendocytosis (see below section entitled “Endocytosis”), it is generallydesirable that layers 524-525 and 526-527 occupy an area as close aspossible to that of layers 520-523, since greater area for thebioelectrocatalysis layers means greater electric power production, forpurposes of driving an IMD's QD-LED.

The purpose of metal layers 525 and 526 is to provide electrical contactwith, respectively, N-type layer 521 and P-type layer 522. Since metallayer 526 is separated from the P-type layer by substrate 520, contactbetween layers 526 and 522 can be accomplished by utilizingThrough-Substrate Vias (or TSV's), as is well-known in the semiconductorfabrication industry. Other than the need for TSV's, metal layers 525and 526 are, in themselves, a common part of QD-LED construction, asdescribed in many publications on this topic, just a sample of whichhave been discussed above: the Coe et al. paper, the Kim et al. paper,and the Baskoutas et al. paper.

Adding bioelectrocatalysis layers 524 and 527, however, in order toprovide a power source for a QD-LED, is one of many inventive techniquespresented herein. The operation of the bioelectrocatalysis layers, as apower source for an IMD, is presented in the following section.

As addressed in an earlier section, an alternative or additional powersource for each IMD can be obtained through broadcast power. In thiscase, metal layers 525 and 526 can be used as a kind of dipole antenna.The tissue into which the IMD's have been injected can be exposed to EMradiation of a suitable frequency, such that sufficient electricalenergy is produced from the dipole antenna (formed from layers 525 and526). For example, a horn antenna can be used to expose the tissue tobroadcast power of sufficient amplitude. While dipole antennas aretypically discussed as a half-wave design, the dipole of an IMD canrepresent a smaller (perhaps much smaller) fraction of the wavelength ofthe broadcast power. Capturing a smaller fraction of the wavelengthmerely reduces the efficiency of the antenna, but the power produced foran IMD can still be sufficient.

8.4 Bioelectrocatalysis

8.4.1 Overview

Assuming bioelectrocatalysis has been selected as the power source (or apower source) of the IMD's to be monitored, this section presents anexample, specific, embodiment for doing so. While the enzyme presentedherein (i.e., NADPH reductase) has been selected to monitor neuralactivity, it can readily be appreciated that other kinds of enzymes canbe substituted, such that other kinds of intracellular activity can bemonitored. For example, with a different enzyme, the bioelectriccatalysis, to power the herein-described IMD, can be switched on when acertain glucose level is reached.

With regard to monitoring neural activity, however, NADPH reductase(produced from NO synthase) can be used as the enzyme of which layer 524is constructed. NADPH reductase is selected because it is activated, asan enzyme, only when the neuron in which it is contained is stronglyactivated (the connection, between neuron activation and enzymeactivation, is explained below). When activated, the NADPH reductaseproduces an electric current at about −0.4 volts (i.e., it is a sourceof electrons). This −0.4 volts is available at metal layer 525 (which iswhy this metal layer is called an anode).

Laccase can be used as the enzyme, of which layer 527 is principallyconstructed. When provided with a source of electrons (i.e., theelectrons provided by the above-described NADPH reductase), the laccaseproduces an electric current at about +0.8 volts. This +0.8 volts isavailable at metal layer 526 (which is why this metal layer is called acathode).

When a neuron is strongly activated, the net voltage between the cathode526 and anode 525 can be expected to be about +1.2 (i.e.,+0.8−−0.4=+1.2). When a neuron is not strongly activated, a relativelynegligible net voltage can be expected to occur, between cathode 526 andanode 525. An example of a separation level, between voltages that arenegligible and those that are not, is the following value: a voltagethat is approximately one order of magnitude smaller, than the netvoltage produced when a neuron is strongly activated. Any voltage thatis equal to or less than this separation level can be regarded asnegligible.

The QD-LED, formed by layers 521-523 and 525-526, is designed, bysuitable selection of materials, to require a V_(TH) that meets both ofthe following constraints:

-   -   V_(TH) is higher than the voltage produced when the neuron is        not strongly activated (e.g., +0.12<V_(TH)); and    -   V_(TH) is less than, or equal to, the voltage produced when the        neuron is strongly activated (e.g., V_(TH)≤+1.2).        The next result, of making V_(TH) meet the above-two        constraints, is that the IMD only emits NIR when the neuron, in        which it is embedded, is strongly activated.

As discussed above, one technique, for changing the threshold V_(TH) ofa QD-LED, is to change the material from which the QD's are formed. A QDformed from CdSe can be expected to have a V_(TH) of about +1.2 volts.Therefore, depending upon the application, thebioelectrocatalysis-supplied power may be regarded as too unreliable,for causing an IMD to emit NIR. For this reason, QD's can be formed fromInAs, which provides a lower threshold voltage. In order to construct aQD-LED that produces a λ anywhere in the NIR range (approximately 700 nmto approximately 1100 nm), the diameter of its InAs QD's should be inthe range of approximately 1.0 nm to approximately 3.0 nm. The smallerdiameters produce higher frequencies, while the larger diameters producelower frequencies. The size range for NIR-generating InAs QD's is basedupon the model in the Baskoutas et al. paper.

The connection, between strong activation of a neuron and activation ofthe NADPH reductase, is as follows. NADPH reductase is activated when itis exposed to an aqueous solution that has a sufficient concentration ofcalcium ions (i.e., Ca²⁺). Research has determined that increasedactivation of a neuron is reliably indicated by its soma achieving anincreased concentration of calcium ions. Only when a neuron reachesstrong activation, however, does its concentration of calcium ionsbecome sufficient to activate NADPH reductase (with the neuron'scytoplasm acting as the aqueous solution to which the NADPH reductase isexposed).

8.4.2 Molecular Level

Although bioelectrocatalysis layers 524 and 527 are shown in FIG. 5A aseach being very similar to its adjacent metal layers, respectively, 525and 526, they are, in fact, quite different. Layer 524 is a type ofcoating, comprised mainly of enzyme molecules attached to metal layer525. Each enzyme molecule is anchored to the metal layer with a simplerlinker molecule. In addition to its anchoring function, each linkermolecule also acts as a kind of “wire,” that guides electrical energy,created in the relative interior of an enzyme molecule, out to the metallayer, where it can be used to power the IMD's QD-LED. Similarly, layer527 is also a kind of coating, comprised primarily of enzyme moleculesthat are attached to metal layer 526. As with layer 524, each enzymemolecule of layer 527 is relatively large and complex. A simpler linkermolecule is used to both anchor each enzyme molecule to layer 526, andto provide a kind of “wire,” for guiding electrical energy from therelative interior of an enzyme molecule.

8.4.2.1 Anode

For the IMD design, as shown in view 504 of FIG. 5B, a corner region531, of layers 524 and 525, is indicated. Region 531 is shown inmagnified form in FIG. 7A. Like FIG. 5B, FIG. 7A continues to show layer525 as a homogeneous metal layer (labeled “anode” in FIG. 7A). Theincreased magnification of FIG. 7A, however, permits layer 524 to beshown quite differently.

Layer 524 is composed primarily of relatively large and complex NADPHreductase molecules (the enzyme). Each NADPH reductase molecule, of FIG.7A, is represented in greatly simplified form as a sphere, rather thanas a ribbon diagram. For each NADPH reductase molecule, only its outerperimeter is indicated, in a first-order approximate way, by thespherical outline. As shown on the right side of FIG. 7A, region 531encloses five NADPH reductase molecules, one of which is labeled 710.The left side of FIG. 7A focuses just upon NADPH reductase molecule 710.

While not specifically shown, each NADPH reductase molecule, comprisinglayer 524, also includes the small molecule cofactor Flavin AdenineDinucleotide (FAD). As part of an IMD manufacturing process, the FAD istypically already added to the NADPH reductase, prior to the NADPHreductase molecules being attached to metal anode 525.

In addition to the NADPH reductase molecules, layer 524 is also shown asincluding linker molecules. For each NADPH reductase molecule, it isanchored to the anode by a corresponding linker molecule. For exampleNADPH reductase molecule 710, as shown on the left side of FIG. 7A, itscorresponding linker molecule is labeled 721. Each linker molecule canbe constructed, for example, from the cofactor Flavin Mono-Nucleotide(FMN).

When activated, the NADPH reductase removes high-energy electrons fromNADPH (already available inside any cell, as a source of energy),converting it into NADP+. At the level of each individual NADPHreductase molecule, the released electrons are first available at themolecule's FAD cofactor, at a location that is relatively interior tothe NADPH reductase molecule. From the FAD, the electrons aretransferred to the FMN linker molecule, which then carries the electronsto the anode. That is why, for linker molecule 721, it is shown asconnecting to a relatively interior point of NADPH reductase molecule710 (that interior location is indicated as “electron transfer” point723). From the anode, the electrons are available as an electriccurrent, in order to power the IMD.

In the above-described electron transfer process, however, the transferfrom the FAD to the FMN only occurs if the NADPH reductase is activated.Calcium ions activate the NADPH reductase by binding to its calmodulin,thereby causing a conformational shift in the structure of the NADPHreductase.

Calcium ions, however, cannot bind to calmodulin at normal intracellularlevels of calcium ion concentration. A neuron's soma only reaches asufficiently high calcium ion concentration when it isstrongly-activated. In particular, during the time when a neuron'spolarization is decreasing, and it is preparing to produce a nextstrong-activation pulse, the requisite calcium ion concentration is onlyreached at, or shortly before, the point in time when depolarization issufficient to cause the neuron to “fire” (i.e., produce an actionpotential). Thus, the calmodulin acts as a kind of calcium concentrationmonitoring element. When the threshold concentration is reached, thecalmodulin acts as a switching element, turning on the electron flow.Once the NADPH reductase has been activated, as discussed above, theNADPH to NADP+ oxidation reaction produces about −0.4 volts.

Binding each linker molecule to the anode (e.g., binding the lowerportion of linker molecule 721 to the anode, as depicted on the leftside of FIG. 7A), can be accomplished by a photochemical bond (e.g.,photochemical bond 722, as indicated on the left side of FIG. 7A). Suchphotochemical bonding is accomplished at an earlier stage of IMDmanufacture.

Such earlier stage is shown in FIG. 7B. In that earlier stage, theentire IMD can first be coated with a photochemical bonding material,over which linker (e.g., FMN) molecules are applied. Where the IMD issubjected to illumination, the photochemical bonding material attacheslinker molecules to the metal layer. Illumination is restricted to onlythe surface of metal layer 525, such that the FMN linker is attachedonly to the IMD's anode. Once the linker molecules are attached, theresidual photochemical bonding material, and the residual linker, can beremoved.

The result is shown in FIG. 7B, where there is simply, at this stage inthe IMD manufacture process, only linker molecules bonded to the anode(as an example, FIG. 7B points to a linker molecule 725, attached to theanode by photochemical bond 724). We shall refer to IMD's, at this stageof manufacturing, as FMN-treated IMD's. The FMN-treated IMD's, and theNADPH reductase, can be combined in a common solution. After the NADPHreductase molecules have attached to the linker molecules of the IMD's,excess NADPH reductase, as well as excess FAD, can be removed withchromatography techniques.

Prior to combining the NADPH reductase and FMN-treated IMD's, the NADPHreductase is (as mentioned above) combined with the FAD. Excess FAD canbe removed with chromatography techniques. During this step, some FADmay attach at NADPH reductase sites that are (if FMN were present) morestrongly compatible with FMN. When the NADPH reductase is combined withthe FMN-treated IMD's (the step described in the previous paragraph),many such FAD molecules can be displaced, causing at least some of theexcess FAD described above.

8.4.2.2 Cathode

For the IMD design, as shown in view 505 of FIG. 5B, a corner region532, of layers 526 and 527, is indicated. Region 532 is shown inmagnified form in FIG. 8A. Like FIG. 5B, FIG. 8A continues to show layer526 as a homogeneous metal layer (labeled “cathode” in FIG. 8A). Theincreased magnification of FIG. 8A, however, permits layer 527 to beshown quite differently.

Layer 527 is composed primarily of relatively large and complex laccasemolecules (the enzyme). Each laccase molecule, of FIG. 8A, isrepresented in greatly simplified form as a cylindrical shape, ratherthan as a ribbon diagram. For each laccase molecule, only its outerperimeter is indicated, in a first-order approximate way, by thecylindrical outline. As shown on the right side of FIG. 8A, region 532encloses four laccase molecules, one of which is labeled 810. The leftside of FIG. 8A focuses just upon laccase molecule 810.

In addition to the laccase molecules, layer 527 is also shown asincluding linker molecules. For each laccase molecule, it is anchored tothe anode by a corresponding linker molecule. For example laccasemolecule 810, as shown on the left side of FIG. 8A, its correspondinglinker molecule is labeled 821.

In order to be active, the laccase depends upon a supply of electronsfrom the cathode (produced by the above-described NADPH reductase). Ifactive, the laccase converts oxygen to water (i.e., converts O₂ to H₂O).As described above, this reduction reaction produces an electric currentat about +0.8 volts. To provide electrons in a way that the laccase canuse, the electrons need to be made available at a location that isrelatively interior to the laccase molecule. That is why, for linkermolecule 821, it is shown as connecting to a relatively interior pointof laccase molecule 810 (that interior location is indicated as“electron transfer” point 823).

Each linker molecule can be constructed, for example, from osmiumtetroxide (OsO₄).

Binding each linker molecule to the cathode (e.g., binding the upperportion of linker molecule 821 to the cathode, as depicted on the leftside of FIG. 8A), can be accomplished by a photochemical bond (e.g.,photochemical bond 822, as indicated on the left side of FIG. 8A). Suchphotochemical bonding is accomplished in an earlier stage of IMDmanufacture. Such earlier stage is shown in FIG. 8B. In that earlierstage, the entire IMD can first be coated with a photochemical bondingmaterial, over which linker molecules are applied. Where the IMD issubjected to illumination, the photochemical bonding material attacheslinker molecules to the metal layer. Illumination is restricted to onlythe surface of metal layer 526, such that the osmium tetroxide linker isattached only to the cathode.

Once the linker molecules are attached, the residual photochemicalbonding material, and the residual linker, can be removed. The result isshown in FIG. 8B, where there is simply, at this stage in the IMDmanufacture process, only linker molecules bonded to the cathode (as anexample, FIG. 8B points to a linker molecule 825, attached to thecathode by photochemical bond 824).

When the laccase and the osmium-tetroxide-treated IMD's are combined ina common solution, a single laccase molecule binds to each linkermolecule of the cathode, and to no other surface of the IMD, resultingin a cathode surface as is shown on the right side of FIG. 8A. Excesslaccase can be removed by chromatography techniques. Laccase isavailable from such companies as MetGen Oy (Kaarina, Finland).

8.5 Endocytosis

Thus far, the path of an IMD, to the inside a cell body, has beendescribed up to the point where an IMD comes into contact with theexterior of the cell membrane. For example, with respect to FIG. 4A, anIMD 420 is depicted as about to contact the exterior wall of one of thesomas that form the cubic region of cells labeled 413.

As has been mentioned above, entry of an IMD into a cell body can beaccomplished by endocytosis. A peptide coating can be added to an IMDsuch that, once the IMD is in contact with a cell wall, endocytosis isinduced. FIG. 9 depicts an example peptide-coating technique, for theIMD structure discussed above with respect to FIG. 5A.

FIG. 9 has three views, labeled 900-902, each of which shows an IMD fromthe same perspective as is shown in view 500 of FIG. 5A. The differencebetween views 900-902, and view 500, is the presence of one or morerings of a peptide, around the anode and bioelectrocatalysis layers(layers 525 and 524). Specifically, view 900 depicts an IMD with asingle peptide ring 910, while view 901 depicts another single peptidering labeled 911. View 902 depicts an IMD with both peptide ring 910 andpeptide ring 911. Peptide ring 910 can be composed of any amphiphilicpeptide, suitable for endosome release, such as the “Palm 1” peptide.For example, see the following publication, herein incorporated byreference in its entirety:

-   -   “Nanoparticle targeting to neurons in a rat hippocampal slice        culture model,” by Walters et al., in ASN Neuro (American        Society for Neurochemistry), Volume 4, September 2012, pages        383-392.        Peptide ring 911 can be composed of any suitable cell permeable        peptide, such as the “Tat” peptide. For example, see the        following publication, herein incorporated by reference in its        entirety:    -   “Different mechanisms for cellular internalization of the HIV-1        Tat-derived cell penetrating peptide and recombinant proteins        fused to Tat,” by Silhol et al., in European Journal of        Biochemistry, Volume 269, January 2002, pages 494-501.

The peptide rings need be applied to only one side of an IMD. Forpurposes of example, FIG. 9 shows the rings around the anode side of anIMD, but the same rings could be applied, instead, to the cathode side(i.e., the side visible in view 501 of FIG. 5A). The peptide coating,forming each of the rings, typically has a depth of only about onepeptide molecule. Attachment of the peptide molecules can beaccomplished using a similar method to that described above, foranchoring a bioelectrocatalysis enzyme molecule with aphotochemically-bonded linker molecule. For each of the peptides to beused, an appropriate linker molecule can be attached to the IMD surface(i.e., to either the N-type layer 521 or substrate 520), by use ofphotochemical bonding. When a peptide is applied to the IMD's surface,its molecules only attach (covalently) at those locations where thecorresponding linker molecule has been bonded.

8.6 Inert Coating

Except for bioelectrocatalysis layers 524 and 527, each IMD can becoated with a material that has at least the following two properties:

-   -   it does not interact with the normal biological processes of the        cell in which the IMD is implanted (i.e., the coating is        biologically inert); and    -   it is transparent to the EM radiation (e.g., NIR) transmitted by        an IMD.

An example coating material, that satisfies these two properties, is theParylene family of compounds, and, in particular, Parylene-C.

Once an IMD has been coated, the peptide rings for inducing endocytosis(discussed in the previous section) can be added.

9 Computing Equipment

In accordance with what is ordinarily known by those in the art, the DSPdescribed herein (e.g., DSP 1160) contains computational hardware (e.g.,integrated circuits), and programmable memories (volatile and/ornon-volatile), of various types.

Computational hardware, whether in integrated circuit form or otherwise,is typically based upon the use of transistors (field effect and/orbipolar), although other types of components (e.g., optical,microelectromechanical, or magnetic) may be included. Any computationalhardware has the property that it will consume energy, as a necessarypart of being able to perform its function. Also, regardless of howquickly it can be made to operate, computational hardware will requiresome amount of time to change state. Because of its basis on physicaldevices (electronic or otherwise), computational hardware, howeversmall, will occupy some amount of physical space.

Programmable memories are also often implemented in integrated circuitform, and are subject to the same physical limitations described abovefor computational hardware. A programmable memory is intended to includedevices that use any kind of physics-based effects or properties, inorder to store information in at least a non-transitory way, and for anamount of time commensurate with the application. The types of physicaleffects used to implement such storage, include, but are not limited to:maintenance of a particular state through a feedback signal, chargestorage, changes to optical properties of a material, magnetic changes,or chemical changes (reversible or irreversible).

Unless specifically indicated otherwise, the terms computationalhardware, programmable memory, computer-readable media, system, andsub-system, do not include persons, or the mental steps a person mayundertake.

The kind of information described herein (such as data and/orinstructions), that is on computer-readable media and/or programmablememories, can be stored on computer-readable code devices embodiedtherein. A computer-readable code device can represent that portion of amemory in which a defined unit of information (such as a bit) can bestored and/or from which a defined unit of information can be retrieved.

10 Glossary of Selected Terms

-   biochemical substance: Any chemical substance that is a part of, or    a result of, the processes of living organisms.-   bioelectrocatalysis: The use of biological materials to produce    oxidation and reduction reactions, resulting in electron transfer.    This typically involves the use of specific enzymes. The result, of    producing bioelectrocatalysis, is an electric current that can be    used to power an electric circuit.-   capsid protein: The protein shell of a virus.-   cell: Unless the context specifically indicates otherwise, any use    of the term “cell” herein is a reference to the basic biological    unit of living organisms. This basic biological unit is enclosed    within a cell membrane, the membrane enclosing (at least) the cell's    cytoplasm, nucleus, and organelles.-   cerebral cortex: the outermost layer of neural tissue, for a    mammalian brain.-   EM: Electromagnetic.-   endocytosis: The process by which a cell absorbs material, initially    external to its cell membrane, by engulfing the material.-   IMD: an Intracellular Monitoring Device, for implantation within a    living cell, that includes at least some microelectronics, and that    is small enough such that it causes no significant impairment to its    enclosing cell's biological processes. The IMD also includes a    transmitter that can transmit data it has collected to a receiver    (or antenna) located external to its enclosing cell.-   “Large Scale Fine Grained” (LSFG) neural monitoring: Across a volume    of cortical-matter large enough to include, at least, thousands of    active neurons, an ability to individually monitor the activity of a    large number of those neurons (e.g., at least hundreds of neurons).-   NCL: Nano-Collimating Lens.-   NIR: Near Infrared. As used herein, NIR refers to a region, of the    EM spectrum, just below the visual spectrum for humans (hence the    “nearness” of NIR), but is still above lower-frequency ranges of    infrared, such as Short-Wavelength Infrared (or SWIR). More    specifically, the NIR referred-to herein is typically in the    wavelength range of approximately 700 μm to 1100 μm.-   nm: Nanometer, or 1.0×10⁻⁹ meters.-   QD: Quantum Dot.-   QD-LED: Quantum Dot Light Emitting Device.-   rat: The “laboratory rat” (or simply “rat”), as described herein,    refers to any one of the commonly and commercially available species    of the Rattus norvegicus, that has been bred for scientific    research. This includes, for example, the Long-Evans laboratory rat.-   μm: Micrometer (or just micron), is 1.0×10⁻⁶ meters.

While the invention has been described in conjunction with specificembodiments it is evident that many alternatives, modifications andvariations will be apparent in light of the foregoing description.Accordingly, the invention is intended to embrace all such alternatives,modifications and variations, as well as those equivalents that fallwithin the spirit and scope of this description and its appended claims.

What is claimed is:
 1. A system for monitoring intracellular activity, comprising: a first intracellular monitoring device that includes a first semiconductor substrate, wherein the first intracellular monitoring device is located completely inside a first cell, and a longest dimension, of the first substrate, is no more than approximately one micrometer; a first P-type layer, manufactured on the first semiconductor substrate; a first N-type layer, manufactured on the first semiconductor substrate; a first quantum dot layer, manufactured on the first semiconductor substrate, and located between the first P-type layer and first N-type layer, wherein a first level of electric current, at a first voltage, when present, is sufficient to cause the first quantum dot layer to emit near infrared electromagnetic radiation that includes at least a first frequency; a first metal layer, manufactured on the first semiconductor substrate, wherein a first side of the first metal layer is in electrical contact with the first N-type layer, and a second side of the first metal layer faces the cytoplasm of the first cell; a second metal layer, manufactured on the first semiconductor substrate, wherein a first side of the second metal layer is in electrical contact with the first P-type layer, and a second side of the second metal layer faces the cytoplasm of the first cell; a first enzyme layer, coating the second side of the first metal layer with a first enzyme, wherein the first enzyme is activated, to produce electrons, by a first concentration of a first biochemical substance, within the cytoplasm of the first cell, that is at least a first threshold level; a second enzyme layer, coating the second side of the second metal layer with a second enzyme, wherein the electrons produced by the first enzyme layer form at least part of the first electric current level, and at least part of the first voltage, when they are received by, and activate, the second enzyme layer; a first antenna, located outside the first cell, that collects near infrared from a plurality of intracellular monitoring devices, wherein a first portion of near infrared collected is from the first quantum dot layer; and an optical domain frequency analyzer, coupled to the first antenna, that detects, at least, a presence of the first frequency in the near infrared collected by the first antenna in order to produce a first frequency specific output.
 2. The system of claim 1, wherein the first cell is a first neuron, the first biochemical substance is a calcium ion, and the first concentration is a calcium ion concentration within the first cell.
 3. The system of claim 2, wherein the first concentration reaching at least the first threshold level is indicative of the first neuron generating a strong action potential.
 4. The system of claim 1, further comprising: a first coating of a peptide, on a first exterior surface of the first intracellular monitoring device, wherein the first coating permits the first intracellular monitoring device, when in contact with an outer membrane of a cell, to induce endocytosis and completely enter a cell.
 5. The system of claim 4, wherein the first peptide, after the intracellular monitoring device has entered the first cell, is digestable.
 6. The system of claim 1, further comprising: wherein the electrons produced by the first enzyme layer form at least the first electric current, and at least the first voltage, when they are received by, and activate, the second enzyme layer.
 7. The system of claim 1, further comprising: a second intracellular monitoring device that includes a second semiconductor substrate, wherein the second intracellular monitoring device is located completely inside a second cell, and a longest dimension, of the second substrate, is no more than approximately one micrometer; a second P-type layer, manufactured on the second semiconductor substrate; a second N-type layer, manufactured on the second semiconductor substrate; a second quantum dot layer, manufactured on the second semiconductor substrate, and located between the second P-type layer and second N-type layer, wherein the first level of electric current, at the first voltage, when present, is sufficient to cause the second quantum dot layer to emit near infrared electromagnetic radiation that includes at least a second frequency; a third metal layer, manufactured on the second semiconductor substrate, wherein a first side of the third metal layer is in electrical contact with the second N-type layer, and a second side of the third metal layer faces the cytoplasm of the second cell; a fourth metal layer, manufactured on the second semiconductor substrate, wherein a first side of the fourth metal layer is in electrical contact with the second P-type layer, and a second side of the fourth metal layer faces the cytoplasm of the second cell; a third enzyme layer, coating the second side of the third metal layer with the first enzyme, wherein the first enzyme is activated, to produce electrons, by the first concentration of the first biochemical substance, within the cytoplasm of the second cell, that is at least the first threshold level; a fourth enzyme layer, coating the second side of the fourth metal layer with the second enzyme, wherein the electrons produced by the third enzyme layer form at least part of the first electric current level, and at least part of the first voltage, when they are received by, and activate, the fourth enzyme layer; wherein the first antenna is located outside the second cell; wherein a second portion, of near infrared collected by the first antenna, is from the second quantum dot layer; and wherein the optical domain frequency analyzer, coupled to the first antenna, detects, at least, a presence of the second frequency in the near infrared collected by the first antenna in order to produce a second frequency specific output.
 8. The system of claim 7, further comprising: a sub-system, including a photodetector, and a digital signal processor configured with programmable memory, that converts the first frequency specific output into a first digital pulse stream, representative of data captured by the first intracellular monitoring device; and a sub-system, including a photodetector, and a digital signal processor configured with programmable memory, that converts the second frequency specific output into a second digital pulse stream, representative of data captured by the second intracellular monitoring device. 